Crying is the dropping of tears (or welling of tears in the eyes) in response to an emotional state or pain. Emotions that can lead to crying include sadness, anger, and even happiness. The act of crying has been defined as "a complex secretomotor phenomenon characterized by the shedding of tears from the lacrimal apparatus, without any irritation of the ocular structures", instead, giving a relief which protects from conjunctivitis. A related medical term is lacrimation, which also refers to non-emotional shedding of tears. Various forms of crying are known as sobbing, weeping, wailing, whimpering, bawling, and blubbering.

For crying to be described as sobbing, it usually has to be accompanied by a set of other symptoms, such as slow but erratic inhalation, occasional instances of breath holding and muscular tremor.

A neuronal connection between the lacrimal gland and the areas of the human brain involved with emotion has been established.

Tears produced during emotional crying have a chemical composition which differs from other types of tears. They contain significantly greater quantities of the hormones prolactin, adrenocorticotropic hormone, and Leu-enkephalin, and the elements potassium and manganese.